Fish Oil and Heart Health

DHA Supplementation Over Two 6-Week Periods

BOSTON, MASSACHUSETTS. Children with inherited hypercholesterolemia (high cholesterol levels) or hyperlipidemia (high cholesterol and triglyceride levels) are at a substantially increased risk for coronary heart disease. It is believed that the main reason for this is that the children have impaired endothelial function resulting in a slowdown in blood flow and a commensurate increase in the risk of atherosclerosis. The quality of endothelial function is determined by measuring endothelium-dependent flow-mediated dilation (FMD) of the brachial artery using high-resolution ultrasound. A normal value for healthy children would be about 8%.

A team of American and Austrian cardiologists has evaluated the effect of supplementation with DHA (docosahexaenoic acid, a main component in fish oil) on FMD in children with hypercholesterolemia or hyperlipidemia. Their double-blind, placebo-controlled, randomized clinical trial involved 20 patients (ages 9-19 years) who were assigned to receive 1.2 grams/day of DHA or a placebo for 2 separate 6-week periods. All participants followed the National Cholesterol Education Program Step II diet throughout the study. At baseline the average FMD was 5.9%. Just following the NCEP-II diet increased the FMD to 6.3%, while adding 1.2 grams/day of DHA supplementation increased it by 34% to a normal level of 7.9%. The average total cholesterol level was 282 mg/dL at baseline and this increased to 297 mg/dL after 6 weeks of DHA supplementation. However, triglycerides decreased from an average of 139 mg/dL to 119 mg/dL (a drop of 14%). Very low-density lipoprotein concentration also decreased by about 23%, while both low-density lipoprotein and high-density lipoprotein increased by 8% and 6% respectively.

DHA Supplementation Restores Endothelial Function in Children

The researchers speculate that the change in cholesterol concentrations may represent a beneficial shift in lipoprotein particle size from the atherogenic, small, dense type to the less atherogenic, large, buoyant type. They also suggest that the observed increase in FMD may be due to increased availability of nitric oxide (NO), which promotes dilation of blood vessels resulting in improved flow. They conclude that DHA supplementation has the potential to delay early coronary atherosclerosis in hyperlipidemic children.
Engler, M.M., et al. Docosahexaenoic acid restores endothelial function in children with hyperlipemia. International Journal of Clinical Pharmacology and Therapeutics, Vol. 42, No. 12, 2004, pp. 672-79

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